Automatic switch as used in telephone systems



Oct. 12, 1943. w. 7R. ROSE v AI JTOMATIC SWITCH AS USED IN TELEPHONE SYSTEM Filed Oct. 7, 1940 R R mm M N0 R ER 0 MM w A Patented Oct. 12, 1943 AUTOMATIC SWITCH AS USED IN TELEPHONE SYSTEMS William Robert Rose, or to The General Coventry, England, assign- Electric Company Limited,

London, England, a British company Application October '7, 1940, Serial No. 360,031

In Great 3 Claims.

The present invention relates to automatic switches of the type used in telephone or like systems and particularly electro-magnetically operated step-by-step switches of the two-directional type.

The invention is more particularly concerned with vertical-and-rotary switches arranged to have normally so-called rectangular motion, that is to say in which release of the Wiper assembly is effected by advancement of the wipers beyond the end of the bank contacts after which they fall and are then rotated back to normal under the bank by spring tension. Such a switch is disclosed in Patent No. 2,028,689, granted January 21, 1936, to R. N. Saxby, and the present invention may be considered as an improvement over that switch. The above-mentioned rectangular release may not always be sufficiently rapid where the switch is required to absorb a digit and in such cases it is possible to provide speedier release by arranging for the wipers to return along the path over which they were set.

A further difficulty arises in such two-directional switches in connection with the restoring of the off-normal springs which are operated when the wiper assembly is stepped off-normal. In the event of the wiper assembly being returned along the same path over which it was stepped and especially when it has been stepped to any early level, it is possible that the said oil-normal springs may not be completely restored to normal because their restoration with this type of release is dependent upon the weight of the switch shaft and the tension of the shaft release spring.

In order to overcome the above-mentioned difficulties it is arranged according to the invention that the wipers after movement in one direction only are returned to normal by means of a separate release magnet which also restores to normal such portion of the ofi-normal springs as can be conveniently restored before the wiper assembly reaches a normal position.

The said separate release magnet which is secured to the switch frame by means of a bracket, preferably consists of a coil fixed to a U-shaped yoke to which is atached by means of a wire spring an armature arranged to operate a rocker arm for the purpose of withdrawing the vertical pawl and vertical detent from the vertical ratchet, the said rocker arm being located on an extension bracket by means of an eccentric adjusting cam located by a screw and nut. Furthermore the armature is arranged to operate a bell-crank lever pivoted on the above-mentioned extension Britain October 16, 1939 bracket, the said lever engaging with an extension arm fitted on the vertical off-normal lever for the purpose of withdrawing the lever when the wiper assembly is returning to normal.

In order that the invention may be more fully appreciated, reference should be made to the accompanying drawing which shows how the switch disclosed by SaXby has been modified to accomplish the desired result. Figure 1 shows a perspective view of the vertical release magnet together with the relevant working parts of the switch. Figure 2 shows a front view of the vertical release magnet and the mechanism by which the vertical pawl and vertical detent are disengaged from the vertical ratchet. Reference may be had to the above-mentioned patent for such elements of the switch structure as form no part of the present invention.

A shaft I, to which is attached a rotary ratchet 2 and a vertical ratchet 3, carries a wiper assembly (not shown), an operating plate 4 and another operating plate 5. The shaft is raised by means of a vertical magnet (not shown) which causes the vertical pawl ID to operate in conjunction with the vertical ratchet. An oilnormal springset 6 and another oiT-normal springset 1 are operated on the first vertical step, the former being operated in well-known manner by means not shown in the drawing and the latter being operated when an off-normal spring operating lever 8 forming part of the plate 5 rides against the side of a cam 9. A vertical detent H which retains the shaft in its operated position during vertical stepping is provided with a vertical detent engaging lug l2.

A vertical release magnet which is secured to the frame by means of a bracket 3| comprises a U-shaped yoke l3, a coil [4 and an armature I5, the said armature being secured to the yoke and held away from the polepiece by means of a single-wire armature restoring spring IS. A bellcrank lever H which is secured to a bracket l8 by means of a bearing pin l9 acts upon an extension arm 26 which is secured by means of rivets or the like to an off-normal spring rest0ring arm 21. The said extension arm moves round a pivot provided by a bearing pin 30. Also secured to the said bracket is a flat spring 20 which bears against a rocker arm 2| which is secured to the bracket by means of an eccentric adjusting cam (not shown) located by a screw 22 and nut 23. The said rocker arm is provided with a vertical pawl releasing lug 24 and a vertical detent releasing lug 25. An armature backstop 29 forms part of the bracket l8.

Considering the detailed operations involved when the switch shaft is raised from its normal position, the operating lever 8 slides against the side of the cam 9 which operates the off-normal springset 1 Whilst at the same time the off-normal springset 6 is operated when the off-normal springset operating lever 23 is raised-the said operating lever disengaging from/another lever (not shown but forming an extension of the arm 21) which removes pressure from the off-normal springset. The flat spring 20 prevents the rocker arm from oscillating during vertical stepping.

Referring now to the sequence of operations involved in restoring the switch shaft to normal after movement in a vertical direction only.

When the vertical release magnet coil [4 is energised, the armature l5 exerts pressure against one end of the bell-crank lever l1 causing the other end of the said lever to rotate the extension arm 26 and the oil-normal spring restoring arm 2], thereby restoring the oil-normal springset 5..

The release magnet armature 15 also exerts pressure against the rocker arm 21 which pushes its vertical pawl releasing lug .24 against :the vertical pawl t0 and causes the vertical pawl ll) to ;be withdrawn from the vertical ratchet 3. Furthermore, the vertical deteni; releasing lug 25 exerts pressure against the vertical detent engaging lug I2 and causes the vertical detentll to withdraw from the vertical ratchet. The shaft now restores to its normal position whereupon the off-normal springset operating'lever *8 takes up a position .-immediately below the cam :9 and allows the off-normal springset 1 to restore.

I'claim:

1. In a two-motion switch, a wiper carrying member movable in two directions, a contact set, means operated by said member for operating said contact set during movement of said member in the first direction, a release magnet operated at times after said member has been moved in said first direction only, means controlled by said manget for restoring said member to normal responsive to said operation of the magnet, and means controlled by said magnet independently of said member for restoring said contact set responsive to said operation of the magnet.

2. A switch as claimed in claim 1, wherein said release magnet includes a yoke, a polepiece, and armature, and a single wire spring for securing said armtaure to said yoke and urging said ar- "matureaway from said polepiece.

3. line two-motion switch having a wiper carrying member movable in two directions, a lever, means operated by said member for operating said lever during movement of said member in the first of .said'directions, a contact set operated by said lever upon said operation of the lever, a release magnet operated at times aftersaid member has been moved in said first direction only, means controlled by said magnet for restoring said wiper carrying member tonormall responsive to said operation of the magnet, a -bellicran k operated lay-said magnet independently of ,said wiper carrying member .upon .said operation of the magnet, and means mechanically linking said bell crank to said lever, thereby to cause said bell cr-ank upon operation to restore said contact set to normal.

WILLIAM ROBERT RGSE. 

